Symptom: Engine lacks power Diagnosis procedures
Yes No
Use an ignition timing lamp to check
ignition timing of engine
Lift it with main stand to have the wheels off the ground. Rotate wheels by hands.
1. Check leakage at external
connection parts of engine;
2.Check valve timing; 3. Check if
valve clearance is too small; 4.
Check tightness between valve
and valve seat; 5.Check if piston
ring is broken or stuck inside the
ring groove or of less elasticity; 6.
Check wear and tear of piston ring
and cylinder.
Start engine and accelerate gradually and
observe variation of engine RPM.
Engine RPM rises as accelerator enlarges Engine RPM does not increase as accelerator enlarges
1. Check if clutch slips; 2. Check if
transmission belt is excessively worn; 3.
Check if the centrifugal roller of driving wheel
is excessively worn; 4. Check if conical
surfaces of driving wheel and mobile friction
wheel is excessively worn or worn to groove;
5. Check if conical surface of driven wheel
and mobile driven wheel are excessively worn
or worn to groove; 6. Check if raceway on the
inner end face of friction wheel is excessively
worn or pitted due to crush.
1. Check if fuel supply system is smooth;
2. Check if carburetor, air cleaner and
exhaust muffler are clogged; 3. Check if
vacuum diaphragm of plunger valve on
carburetor is cracked or broken; 4. Check
if height of carburetor float is proper.
1. Check CDI
igniter. 2. Check if
magneto flywheel
or trigger coil
looses.
Engine lacks power
Wheels rotate freely.
Wheels rotate inflexibly.
Check tire pressure 1. Check braking drag; 2. Check if
bearing of wheels are over worn or
injured; 3. Check if the middle spacers in
the hub are missed or short.
Air pressure too low Air pressure normal
Check if valve core leaks
or tyre is broken.
Remove spark plug and block the screw hole of spark plug with a
finger. Press starter button or kick starter pedal.
Finger can feel strong air blasting out
and meantime make a pitpat sound
Finger cannot feel strong air blasting out.
Compression pressure in the cylinder is normal.
Compression pressure in the cylinder is not enough.
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